Acting FBI Director Andrew McCabe testifies before the Senate Intelligence Committee with the other heads of the U.S. intelligence agencies in the Hart Senate Office Building on Capitol Hill May 11, 2017 in Washington, DC.

The emails were discovered on the laptop of disgraced Rep. Anthony Weiner — but there was no action from the FBI until about three weeks later in October, just before the election, according to the report. Democrats and Trump opponents have suggested the FBI's announcement about the emails, which came just days before the election, helped sway the race toward Donald Trump.

The Post says the period of inaction raised the question of whether FBI leadership wanted to avoid publicizing the emails until after the Nov. 8 presidential election between Clinton and Trump.

McCabe, sources familiar with the matter told the Post, is a key figure in the DOJ's inquiries into who knew about the email and when. The inspector general, Michael Horowitz, had announced his investigation into the FBI's handling of the Clinton investigation shortly after the election and before Trump fired FBI Director James Comey.

McCabe on Monday abruptly resigned from his position in the bureau. Trump has often targeted McCabe for perceived political bias toward Democrats and Clinton. McCabe's wife had reportedly received hundreds of thousands of dollars in political contributions from Clinton ally and then-Virginia Gov. Terry McAuliffe for a 2015 run for the state legislature.

The Justice Department did not immediately respond to a request for comment.